Hmm, if all of the system paths are correct on the initial screen and the user can connect to the database I'm not entirely sure; you're positive that the user account has permission to write to the database and is connecting via localhost (or the user accounts ip is correct for their access permissions if you're using a secondary server to host a database).
Do you by chance have any security extensions installed on your browser that could be stopping variables from being passed between webpages?